I haven't tried them; they do look like they would work very well.
I already have many excellent sanding and polishing sticks of various shapes and sizes that I bought fairly cheap because I was man enough to walk into a beauty supply shop
Whether a beauty supply shop or the nailcare section at a department store, there are great sanding/polishing supplies suitable for modelers, and kits for repairing broken fingernails are also good for repairing or securing major bodywork.
One could easily get the impression someone else figured this out, buys them from wholesale beauty suppliers, and resells them to hobbiests at a significant markup
Just a heads-up that cool modeling supplies may be easier to find than you thought.